Gyrocompass



May 3 1967 SH|N-|CH| KAWADA GYROCOMPASS 4 SheetsShe et 1 Filed June 18, 1964 IN V EN TOR. -10 1%? wzma May 30, 1967 Filed June 18, 1964 SHINICH| KAWADA GYROCOMPAS S 4 Sheets-Sheet 2 O INVENTOR. 67w f0/2 r lawaaa y 1967 SHlNflCHI KAWADA GYROCOMPAS S 4 Sheets-Sheet 3 Filed June 18, 1964 INVENTOR. S'1Wm1h/ A awada May 30, 196'? SHIN-ECHI KAWADA 3,321,841

GYROCOMPASS Filed June 18, 1964 4 Sheets-Sheet 4 IN V EN TOR.

6% in Jww' We Mada BY 4 W United States Patent Oilicc 3,321,841 GYRQCOMFASS Shin-Ichi Kawada, Yokohama-shit, Japan, assignor to hiahushilrikaisha Tokyo Keiiri Seizosho (Tokyo Keiiii Seizoslro $0., Ltd), Tokyo, Japan, a corporation of Japan Filed June 13, 1964, Ser. No. 376,020 Claims priority, application Japan, June 19, 1963, 38/331,220 4 Claims. (Cl. 333-226) This invention relates to improvements in well-known gyrocompasses having a north-seeking action due to a mercury ballistic or a liquid ballistic and a damping system which applies a torque to a vertical shaft in proportion to gyro-inclination.

One object of this invention is to provide a gyrocompass in which latitude errors are prevented which are peculiar to usual gyrocompasses mentioned above.

Another object of this invention is to provide a gyrocompass in which mass unbalance about a horizontal axis of a sensitive element is prevented from occurring which is caused due to temperature change and with the lapse of time, thereby to avoid errors due to the unbalance.

Another object of this invention is to provide a gyro compass in which a torque about a horizontal axis is pre' vented from occurring which is due to a flexible wire for flowing current for driving a gyro, thereby to avoid errors due to the torque.

Other objects, features and advantages of this invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a graph for explaining the north-seeking action of a gyrocompass heretofore employed;

FIGURE 2 is a schematic diagram illustrating an example of an integral torque generator which may be used in the present invention;

FIGURE 3 is a diagram fundamentally illustrating an embodiment of the present invention;

FIGURE 4 is a graph, similar to FIGURE 1, for explaining the north-seeking action of a gyrocompass of the present invention;

FIGURE 5 is a perspective view schematically illus trating an embodiment of the gyrocompass of the present invention, having one portion removed.

FIGURES 6 to 9, inclusive, are schematic diagrams showing other integral torque generators which may be used in the present invention; and

FIGURES 10 and 11 are schematic diagrams each illustrating one portion of the integral torque generator.

Before entering into the explanation of the present invention in detail, a conventional type gyrocompass will hereinbelow be explained simply which is provided with a mercury ballistic or a liquid ballistic (hereinafter referred to as a ballistic) and a device which applies a torque about a vertical axis of the gyrocompass in proportion to gyro inclination.

In all the conventional type gyrocompasses, their gyrospin axes are not correctly horizontal with respect to the surface of the earth when the gyrocornpasses set still pointing substantially to the north, and in northern hemisphere their north-side ends of spin axes are a ittle higher than the south-side ones. In the conventional type compass provided with the ballistic, the liquid of the ballistic flows to a pot of the south side which is lower than the north side and accordingly the south side becomes a little heavier than the north side, thereby producing a torque around a horizontal axis crossing the spin axis of the gyro at the right angle. With this torque, the gyro causes a preces sion around the vertical axis thereof. The angular velocity of the precession coincides with an angular velocity around the vertical axis of the surface of the earth at that place and the surface of the earth and the gyro rotate together,

3,321,841 Patented May 30, 1967 so that the gyro is regarded to stand still, pointing substantially to the north, withv respect to the surface of the earth. That is, in the conventional type gyrocompass the inclination of the gyro spin axis from the horizontal level differs in accordance with the location of the gyrocompass and this inclination depends upon only the latitude of the location, and the spin axis is horizontal at the equator and the south side thereof becomes higher than the north side in the southern hemisphere.

As a damping system for making a gyro stationary toward the north, there is employed a method to apply a torque about a vertical axis in proportion to gyro inclination. According to this method, however, the position that the gyro inclines becomes a stationary point except at the equator, and hence a damping torque produced about the vertical axis remains at the stationary point. As a result of this, the gyro axis does not point to the due north, producing an error. This error is related only to the latitude in its nature, more correctely, it is proportional to the tangent of latitude and it has long been referred to as a latitudinal error.

If now a conventional gyrocompass is started from a position that its gyro spin axis tilts toward the east by an angle from the north and its north side lies lower an angle 0 than the south side, the spin axis performs damped oscillation as shown by the azimuthal curves :2 and b in FIGURE 1 due to the action of a ballistic and a damping device and then comes to a standstill at a position that the north side of the axis is higher than the south side by 0 producing an error (a latitudinal error) of gi in azimuth. In FIGURE 1, the abscissa expresses time t in unit time T and the ordinate expresses an azimuth (the east) and an angle of inclination 0 (the north).

In this kind of gyrocompasses, errors are produced even by transfer of the center of gravity which is caused due to temperature rise of the gyro and the like and with the lapse of time. This is because of the fact that when the gyrocompass comes to a standstill toward the north, precession around its vertical axis coincides with the rotary component around the vertical axis of the earth at a place where the gyrocornpass is located for the reasons described above and a torque must be produced from a ballistic for eliminating a torque around the horizontal axis of the gyrocompass and, as a result of this, gyroinclination becomes different at the stationary point. For the same reasons, all the inherent torque produced around the horizontal axis cause constant errors.

in view of the foregoing disadvantages, the present invention is to provide means for obtaining highly eflicient gyrocompasses without the accompanying errors.

In FIGURE 2, an integral torque generator is generally indicated at a reference U which is an example of an element of this invention. In this example the integ al torque generator U is such that a highly viscous liquid 2 is enclosed in a cylindrical sealed vessel 1 and a bubble 3 is formed there n. That is, this integral torque generator is similar to a usual bubble-type level. However, a difference therebetween resides in that the inner surface 4 of the vessel 1 with which the bubble 3 gets in touch is not curved but straight in the present example. The inner surface of a vessel of the usual level is curved. In other words, the inner surface 4 of this example is exactly cylindrical. Therefore, when the inner surface 4 is horizontal the bubble 3 can rest at any position and when the surface 4 is inclined the bubble 3 always moves on to- Ward 21 higher end of the vessel 1 and it cannot rest on the way. A second difference between the present invention and the usual level is that the liquid 2 is of relatively high viscosity, and accordingly moving speed of the bubble 3 is exactly proportionate to the inclination of the cylindrical surface t. That is, the position of the bubble 3 of this example shown in FIGURE 2 is in proportion to an integrated value of the inclination of the surface 4 with respect to time. At the same time, the position of the center of gravity varies proportionally in response to travel of the bubble 3, so that this also is proportionate to the integrated value of the inclination of the surface 4.

With reference to FIGURE 3, the principle of the present invention will hereinbelow be explained that the aforementioned integral torque generator U is applied to a gyrocompass.

In FIGURE 3, 5 indicates a gyro case enclosing a gyro, and a gyro-spin axis is on the line AB. 6 is a ballistic consisting of a pair of pots 7 and 8 and an interconnecting pipe 10, in which a liquid 9 is enclosed The ballistic 6 and the gyro case 5 move as one body about a shaft ll'crossing the line AB at the rig-ht angle as in compasses heretofore employed. Where the integral torque generator U described in FIGURE 2 is attached to the gyro case 5 in parallel to the line AB as illustrated in FIGURE 3, transfer of the center of gravity of the integral torque generator U acts on the gyro as a torque about the horizontal shaft 11. Even if the torque has reached a maximum value when the bubble 3 stay at the one end of the vessel, so far as the viscosity of the liquid 2 is so selected that the torque is sufficiently smaller than that produced by the ballistic 6 and that the moving speed of the bubble 3 is sufficiently small as compared with that of the liquid in the ballistic 6, the spin axis of this gyro moves to rest toward substantially the north as shown by the curve in FIGURE 1 owing to the action of the ballistic 6 and a damping device not shown. In the northern hemisphere, however, the spin axis AB cannot rest unless it inclines with its north side a little higher. Accordingly, when the gyro-spin axis is about to rest substantially toward the north the spin axis always comes to be in a condition that its north side is higher than the south side. That is, since the spin axis moves in the same manner as the curve in FIGURE 1, when the motion draws to a standstill the bubble 3 gradually and accurately moves on toward the north side and transfer of the center of gravity of the integral torque generator U produces a torque which gradually pushes down the south side toward the direction of gravity. Thus the gyro comes down to the north and continues the north-seeking action so that the torque of the integral torque generator U may be eliminated by a torque produced by the ballistic 6. Thus, a stable stationary point of this gyro is inevitably determined in the following manner. That is, the stable point is such that the torque of the integral torque generator U is constant and a difference between this torque and that of the ballistic 6 remains as a constant torque around the horizontal shaft 11 and precession caused by the resultant torque coincides with the rotary component around the vertical axis of the surface of the earth at the place where the gyro is located. In other words, the position that the torque of the integral torque generator U becomes constant is a position that the spin axis stays horizontal. In such a case, the liquid of the ballistic 6 is kept in an equilibrium in the pots 7 and 8 and a torque of the ballistic 6 is zero. The bubble 3 of the integral torque generator U stands still at a place on the north side and a torque around the horizontal shaft due to transfer of the center of gravity becomes a value corresponding to precession around the vertical axis of the gyro which is equal to the vertical component of rotation of the earth at that place. Thus, by the use of the integral torque generator U the stationary point of the gyro-spin axis is correctly horizontal, so that the torque around the vertical axis produced by the damping system is also zero at the stationary point and therefore no latitudinal errors are produced. That is, the north-seeking action of the gyrocompass using an integral torque generator which corresponds to that in FIGURE 1 is as illustrated by the curves a and b in FIGURE 4 corresponding to those in FIGURE 1.

FIGURE 5 illustrates an embodiment of the present invention, which is shown simple in structure for explaining the principle of this invention. A gyro case 5 similar to that in FIGURE 3 has vertical shafts 13 and 13', which are supported to a vertical ring 14 by means of ball bearings not shown in the figure. The vertical ring 14 is in turn supported to a horizontal ring 18 by horizontal shafts 11 and 11 through ball bearings not shown. Furthermore, the horizontal .ring 18 is supported to a follower ring 20 by shafts 19 and 19 through ball bearings not shown. This follower ring 20 is supported to a case 28 by shafts 21 and 21. The vertical ring 14 has a support base 15, from which the vertical shaft 13 is suspended by a suspension wire 16, so that the weight of the gyro case 5 does not render any load to the vertical shaft bearings. To the vertical ring 14, a ballistic 6 including pots 7 and 8 and a communication pipe 10 such as illustrated in FIGURE 3 is fixed by a support arm 17. The pots 7 and 8 have an air pipe 12 and a non-contact pick-off 23 is provided between the vertical ring 14 and the gyro case 5 to detect relative displacement between the ring 14 and the case 5, forming a servo loop through an amplifier (not shown), a servo motor 25, toothed wheels 29 and 22 and through the follower ring 20 and the horizontal ring 18 connected to the toothed wheel 22. As a result of this, the gyro case 5 and the vertical ring 14 are always in motion together and controlled by the servo system so that no displacement may be caused therebetween. Thus, the azimuth of the spin axis can be read out from a dial card 26 attached to the shaft 21 with respect to an index 27.

In this case, the gyro case 5 and the ballistic 6 are put in the same state around the horizontal shaft 11 as in FIG- URE 3. A damping system is formed by a counterweight 24. That is, the counter-weight 24 is mounted on the west side of the gyro case 5 and produces a torque around the vertical shafts 13 and 13 in proportion to inclination of the gyro case, which acts as a damping action as has been well known. In FIGURE 5, the gyro faces toward the south and rotates in the clockwise direction.

The above is, by way of example, the structure of the gyrocompass to which the present invention is applied. Furthermore, in FIGURE 5 an integral torque generator U such as described in FIGURE 2 is mounted on the vertical ring 14 in parallel to the gyro-spin axis. That is, since the integral torque generator U can move about the horizontal shafts 11 and ll integrally with the ballistic 6 and the gyro case 5 exactly in the same manner as that previously described in connection with FIGURE 3, it will be seen that the gyrocompass in FIGURE 5 comes to a standstill horizontally toward the due north as explained in FIGURE 3. Even if the integral torque generator U is mounted directly on the gyro case 5 in the example shown in FIGURE 5, its action is exactly the same; In accordance with the kind of a damping system used, the integral torque generator U can be mounted on the gyro case 5 or a portion which supports it and moves about the same horizontal shaft as one body with the gyro case and the ballistic.

Many other kinds of integral torque generators may be used without being limited to that shown in FIGURE 2. Several examples of the integral torque generator will hereinbelow be explained which are different from that in FIGURE 2.

FIGURE 6 illustrates an integral torque generator U which is different from that shown in FIGURE 2 and its vessel and viscous liquid contained therein are the same as those in FIGURE 2 and therefore marked with the same reference numerals, but mercury indicated at 30 is enclosed in the vessel 1. Its specific gravity i larger than the viscous liquid 2 and goes down under the viscous liquid 2 and coheres due to its surface tension as illustrated in the figure. In this case, the inner surface 4 of the vessel 1 with which the mercury 30 gets in touch is the same as that in FIGURE 2. Also in the example shown in FIGURE 6, when the surface 4 inclines the mercury 39 moves on to a lower end of the vessel 1 and its speed is determined in accordance with the viscosity of the liquid 2 and inclination of the vessel 1. The center of gravity of the whole unit varies in proportion to an integrated value of the inclination with respect to time and this integral torque generator can be used as an integral torque generator U having the same effect as that described above in connection with FIGURE 2. It will be understood that generally a liquidus material having large surface tension and larger specific gravity than that of the viscous liquid 2 can be used instead of the mercury ball.

FIGURE 7 is another integral troque generator which is different in structure from the above one, and a solid ball 31 is enclosed in a vessel 1 filled with a highly viscous liquid 2. When the inner surface 4 inclines the solid ball 31 also moves on to a lower end of the vessel 1 at a speed proportionate to the inclination.

Since the integral torque generator U shown in FIG- URE 2 makes use of the bubble 3, it is extremely precise in operation but it is not so suitable for obtaining a large torque. In the integral torque generators U illustrated in FIGURES 6 and 7 their moving members are of large specific gravity, so that resultant torque is far larger than that by the generator U in FIGURE 2, even if the vessel is relatively small.

FIGURE 8 is an example in which. friction is reduced and removed between a moving member 31 and the inner surface 4 of a vessel 1 in the integral torque generator U previously described in FIGURE 7. The vessel 1 consists of a cylinder 32, lids 33 and 34 and shafts 35 and 36, and the center line of the shafts 35 and 36 is exactly along the axis of the cylinder 32. The vessel 1 has therein a highly viscous liquid 2 which is the same as that in FIG- URE 7 and a solid ball 31. The shafts 35 and 36 are supported by ball bearings 37 and 33 which are mounted respectively stems 39 and 40 standing on the base 41. A motor 42 is also fixed on the base 41 and its rotation is transmitted to the vessel 1 through a pinion 43 and a gear 44. As is apparent from the figure, when the motor is rotated to thereby revolve the vessel 1 at a suitable speed the solid ball 31 is rotated due to the viscosity of the liquid 2 and an oil film intervenes between the ball 31 and the inner surface 4. When increasing the speed of rotation further, the solid ball 31 rises upon the liquid, so that the inner surface 4 and the ball 31 does not get in contact with each other directly and accordingly friction between them can be removed. It is not difiicult to fix the entire device shown in FIGURE 8 on the gyro case 5 or on the.

portion of its support member, and a power source of the motor 42 can be led from gyro-driving power source.

The device in FIGURE 8 can similarly be made use of with the integral torque generator U shown in FIGURE 6. Furthermore, it is not always necessary to rotate the vessel 1 in one direction but as apparent from the foregoing explanation, it will be also possible merely to turn it periodically in forward and backward directions at a certain amplitude.

FIGURE 9 illustrates another integral torque generator U, in which support bases 46 and 47 are provided on a base plate and ball bearings 48 and 49 are fitted in the support bases 46 and 47 thereby to support a shaft 50 rotatably. To the shaft 50, a support arm 51, a counterweight 52 and a damper 53 are fixed, and the free end of the damper 53 is inserted into a viscous liquid 55 contained in a box 54. The portion including the shaft 50, the support arm 51, the counter-weight 52 and the damper 53 is in contact with only the ball bearings and the viscous liquid 55 without directly contacting the base plate 45 and the box 54-.

When the device is positioned in such a manner that the shaft 50 is directed to gravity the counterweight 52 does not produce any torque large enough to rotate the shaft 50. If now the base plate 45 is supported on the horizontal axis X-Y and its one side OA inclined to be 0A or CA", the counter-weight 52 produces a torque around the shaft 50. This torque is opposite in direction according to the inclinations of the one side to 0A and 0A". Since the damper 53 is inserted into the highly viscous liquid 55, the rotating speed of the weight. 52 around the shaft 50 becomes proportionate to an angle of inclination of the side CA from its initial position. At the same time, change of the center of gravity of the whole device in FIGURE 9 corresponds to the inclination.

Therefore, if the device shown in FIGURE 9 is fixed to the gyro case or one portion of its support member in such a manner that when the gyro-spin axis is horizontal the shaft 5% is vertical and the support arm 51 crosses the spin axis substantially at the right angle, the device of FIGURE 9 can act as an integral torque generator U exactly in the same manner as the aforementioned devices.

The integral torque generator illustrated in FIGURE 9 can be generally explained as follows:

A member is journalled on the vertical shaft 50 at its one side and the other part thereof is immersed into a viscous liquid. If the vertical shaft 50 inclines with respect to its vertical position, the member is rotated about the shaft 50, which causes the transfer of the center of gravity of the member.

FIGURES 10 and 11 illustrate improvements of the device shown in FIGURE 9, each showing merely some portions around the shaft 50 of the device of FIGURE 9. In FIGURE 10 a support base 56 is provided on the upper portion a base plate 45, from which is suspended a suspension wire 57 such as a piano wire or the like. The suspension wire 57 is fixed to the shaft 50 exactly along the extension axis of the shaft 50, by which no thrust load is produced in bearings 48 and 49 to reduce extreme friction of the ball bearings 48 and 49, thereby making it possible to increase precision. However, if a torque due to torsion of the suspension wire 57 increases to such an extent that it cannot be neglected, its influence appears. FIGURE 11 is a device in which a float is provided at the lower end of a shaft 50 so as not to produce a torsional torque the float is floated by a liquid 6% inside a vessel 58 attached to a base plate 45. Also in this case, friction between bearings 4-8 and 49 can be decreased. Furthermore, the damper 53, the box 54 and the liquid 55 in FIGURE 9 can be dispensed with by the use of a highly viscous liquid as the liquid 60.

According to the present invention, a device in which the device itself causes transfer of the center of gravity in proportion to an integrated value of inclination is attached to a sensitive element of a gyrocompass whereby no latitudinal errors are caused and gyrocompasses of high precision can be manufactured at a low price. Consequently the present invention is very valuable for practical use in the operation of ships.

The gyrocompasses to which this invention can be applied are well-known ones of the same: kind without being restricted to that shown in FIGURE 5. As to the ballistic, not only mercury and liquid type ones but also the so-called top-heavy type ones using viscosity and a pendulum can be employed.

The clamping device of this invention can also be applied not only to the damping weight system shown in FIGURE 5 but also to an easterly eccentric pivot system, an air control system or the like such that a torque is applied to the vertical shaft to effect damping. The gyro supporting system can also be applied to other ones. Since these well-known gyrocompasses are not related directly to the present invention, explanations thereon are omitted from the specification. However, it will be seen that so far as this invention can be applied to them, they fall within the scope of the present invention.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concept of this invention.

What is claimed is:

1. A gyrocompass comprising:

a case;

a rotor mounted in said case for rotation about a first horizontal axis;

a support member including means connected to said case and providing an axis of rotation of said case and said rotor mounted therein along a second horizontal axis which is perpendicular to said first horizontal axis, said case having a vertical axis passing therethrough and intersecting said first and second horizontal axes at right angles thereto; and

an integral torque generator secured to said means so as to be movable with said case and said rotor about said second axis to produce a torque with respect to time to eliminate the effects of latitudinal error which is caused by the earth rotation, said integral torque generator including a cylindrical vessel, a highly viscous liquid sealed within said cylindrical vessel, a mass positioned within said cylindrical vessel and in contact with said viscous liquid, shaft means secured to said cylindrical vessel at opposite ends thereof to provide an axis of rotation for said cylindrical vessel, and means for rotating said cylindrical vessel about said axis of rotation, whereby said viscous liquid will cause said mass to be suspended therein.

2. A gyrocompass comprising:

a case;

a rotor mounted in said case for rotation about a first horizontal axis;

a support member including means connected to said case and providing an axis of rotation of said case and said rotor mounted therein along a second horizontal axis which is perpendicular to said first hori zontal axis, said case having a vertical axis passing therethrough and inserting said first and second horizontal axes at right angles thereto; and

an integral torque generator secured to said means so as to be movable with said case and said rotor about said second axis to provide a torque with respect to time to eliminate the efiects of latitudinal error which is caused by the earth rotation, said integral torque generator including a cylindrical vessel, a highly viscous liquid sealed within said cylindrical vessel, a mass sealed within said cylindrical vessel and in contact with said viscous liquid, and means connected to said cylindrical vessel for periodically rotating said cylindrical vessel about its axes to cause a film of viscous liquid to be created between the inner surface of cylindrical vessel and said mass.

3. A gyrocompass comprising:

a case;

a rotor mounted in said case for rotation about a first horizontal axis;

a support member including means connected to said case and providing an axis of rotation of said case and said rotor mounted therein along a second horizontal axis which is perpendicular to said first horizontal axis, said case having a vertical axis passing therethrough and intersecting said first and second horizontal axes at right angles thereto;

alignment means connected to said support member for orientating said first horizontal axis'in a north-south direction;

damping means connected to said case for supplying a damping torque to said gyro about said vertical axis, which damping torque is proportional to the inclination of said first horizontal axis;

the improvement therein comprising an integral torque generator secured to said means of said support member so as to be movable with said case and said rotor about said second horizontal axis to produce a torque with respect to time to eliminate the effects of latitudinal error which is caused by the earth rotation, said integral torque generator including a cylindrical vessel, a viscous liquid carried within the interior of said vessel, a mass positioned within said vessel and in fluid contact with said liquid, shaft means secured to said vessel to provide an axis of rotation of said vessel, and means connected to said vessel for rotating said vessel about said axis of rotation so as to suspend said mass in said liquid.

4. In a gyrocompass comprising:

a case;

a rotor mounted in said case for rotation about a first horizontal axis;

a support member including means connected to said case and providing an axis of rotation of said case and said rotor mounted therein along a second horizontal axis which is perpendicular to said first horizontal axis, said case having a vertical axis passing therethrough and intersecting said first and second horizontal axes at right angles thereto;

alignment means connected to said support member for orientating said first horizontal axis in a northsouth direction;

damping means connected to said case for supplying a damping torque to said gyro about said vertical axis, which damping torque is proportional to the inclination of said first horizontal axis;

the improvement therein comprising an integral torque generator secured to said means of said support member so as to be movable with said'case and said rotor about said second horizontal axis to provide a torque with respect to time to eliminate the effects of latitudinal error which is caused by the earth rotation, said integral torque generator including a cylindrical vessel, a viscous liquid carried within said vessel, a mass suspended within said vessel and in fluid contact with said liquid, and

means connected to said vessel for periodically rotating said vessel first in one direction and then in another direction so as to cause a film of liquid to exist continously between said mass and the interior of said vessel.

References Cited UNITED STATES PATENTS 1,777,958 10/ 1930 Brown 33--226.5 1,805,854 5/1931 Sperry 33--226.5 1,866,706 7/1932 Henderson 33-2265 1,923,885 8/1933 Rawlings 33--226.5 2,249,345 7/ 1941 Braddon 33-2265 3,212,196 10/1965 Carter 33--226 LEONARD FORMAN, Primary Examiner.

W. D, MARTIN, Assistant Examiner, 

1. A GYROCOMPASS COMPRISING: A CASE; A ROTOR MOUNTED IN SAID CASE FOR ROTATION ABOUT A FIRST HORIZONTAL AXIS; A SUPPORT MEMBER INCLUDING MEANS CONNECTED TO SAID CASE AND PROVIDING AN AXIS OF ROTATION OF SAID CASE AND SAID ROTOR MOUNTED THEREIN ALONG A SECOND HORIZONTAL AXIS WHICH IS PERPENDICULAR TO SAID FIRST HORIZONTAL AXIS, SAID CASE HAVING A VERTICAL AXIS PASSING THERETHROUGH AND INTERSECTING SAID FIRST AND SECOND HORIZONTAL AXES AT RIGHT ANGLES THERETO; AND AN INTEGRAL TORQUE GENERATOR SECURED TO SAID MEANS SO AS TO BE MOVABLE WITH SAID CASE AND SAID ROTOR ABOUT SAID SECOND AXIS TO PRODUCE A TORQUE WITH RESPECT TO TIME TO ELIMINATE THE EFFECTS OF LATITUDINAL ERROR WHICH IS CAUSED BY THE EARTH ROTATION, SAID INTEGRAL TORQUE GENERATOR INCLUDING A CYLINDRICAL VESSEL, A HIGHLY VISCOUS LIQUID SEALED WITHIN SAID CYLINDRICAL VESSEL, A MASS POSITIONED WITHIN SAID CYLINDRICAL VESSEL AND IN CONTACT WITH SAID VISCOUS LIQUID, SHAFT MEANS SECURED TO SAID CYLINDRICAL VESSEL AT OPPOSITE ENDS THEREOF TO PROVIDE AN AXIS OF ROTATION FOR SAID CYLINDRICAL VESSEL, AND MEANS FOR ROTATING SAID CYLINDRICAL VESSEL ABOUT SAID AXIS OF ROTATION, WHEREBY SAID VISCOUS LIQUID WILL CAUSE SAID MASS TO BE SUSPENDED THEREIN. 